Sheet for mounting polishing workpiece and method for making the same

ABSTRACT

The present invention relates to a sheet for mounting a polishing workpiece. The sheet comprises a substrate, a surface layer and a slightly rough layer. The substrate has a surface. The surface layer is located on the surface of the substrate, with no hole structure existing in the interior thereof, and has a surface. The slightly rough layer is located on the surface of the surface layer to carry and mount the polishing workpiece, with no hole structure existing in the interior thereof. Accordingly, when the polishing workpiece contacts the slightly rough layer, the air therebetween is easily vented out via the slightly rough layer, without the phenomenon of air wrapping, which increases the adsorption force between the polishing workpiece and the sheet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 11/478,601, filed Jul. 3,2006, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet for mounting a polishingworkpiece and the method for making the same, and more particularly, toa sheet for mounting a polishing workpiece and the method for making thesame which are used in the chemical mechanical polishing process.

2. Description of the Related Art

Polishing generally refers to a wear control for a preliminary coarsesurface in the process of chemical mechanical polishing (CMP), whichmakes the slurry containing fine particles evenly dispersed on the uppersurface of a polishing pad, and at the same time places a polishingworkpiece against the polishing pad and then rubs the workpiecerepeatedly with a regular motion. The polishing workpiece may be objectssuch as a semiconductor, a storage medium substrate, an integratedcircuit, an LCD flat-panel glass, an optical glass and a photoelectricpanel. During the polishing, a sheet must be used for carrying andmounting the polishing workpiece, and the quality of the sheet directlyinfluences the polishing effect of the polishing workpiece.

Referring to FIG. 1, a schematic view of a polishing device with aconventional sheet disclosed in U.S. Patent No. U.S. Pat. No. 5,781,393is shown. The polishing device 1 comprises a lower base plate 11, asheet 12, a polishing workpiece 13, an upper base plate 14, a polishingpad 15 and slurry 16. The sheet 12 is adhered to the lower base plate 11through an adhesive layer 17 and is used for carrying and mounting thepolishing workpiece 13. The polishing pad 15 is mounted on the upperbase plate 14.

The operation mode of the polishing device 1 is as follows. First, thepolishing workpiece 13 is mounted on the sheet 12, and then both theupper and lower base plates 14 and 11 are rotated and the upper baseplate 14 is simultaneously moved downwards, such that the polishing pad15 contacts the surface of the polishing workpiece 13. A polishingoperation for the polishing workpiece 13 may be performed bycontinuously supplementing the slurry 16 and using the polishing pad 15.

Referring to FIG. 2, a local schematic view of the sheet of FIG. 1 isshown. The sheet 12 is of a single-layer structure, the material ofwhich is generally PU (polyurethane), a kind of foaming material. Thesheet 12 is formed by a wet process, and thus a plurality of continuousfoaming holes 121 exists in the interior of the sheet 12. Thedisadvantage of the sheet 12 is that the slurry 16 tends to be inhaledthrough the foaming holes 121 during the polishing process, which causeschanges in the hardness and physical property of the sheet 12, such thatthe polishing condition needs to be readjusted. Furthermore, thelifetime of the sheet 12 is reduced. In addition, the sheet 12 is formedby the wet process which results in an excessively low planarity, and itis very difficult to achieve a generally uniform thickness above 0.5 mm.Finally, the foaming holes 121 within the sheet 12 cause the phenomenonof air wrapping when the sheet 12 adsorbs the polishing workpiece 13,thus resulting in a poor adhesion and a possible crack during thepolishing process as well as an uneven polished surface after thepolishing of the polishing workpiece 13.

Consequently, there is an existing need for a sheet for mounting apolishing workpiece and the method for making the same to solve theabove-mentioned problems.

SUMMARY OF THE INVENTION

The objective of the present invention is to provide a sheet formounting a polishing workpiece. The sheet of the present inventioncomprises a substrate, a surface layer and a slightly rough layer. Thesubstrate has a surface. The surface layer is located on the surface ofthe substrate, with no hole structure existing in the interior thereof,and has a surface. The slightly rough layer is located on the surface ofthe surface layer to carry and mount the polishing workpiece, with nohole structure existing in the interior thereof. Accordingly, when thepolishing workpiece contacts the slightly rough layer, the airtherebetween is easily vented out via the slightly rough layer, withoutthe phenomenon of air wrapping, which increases the adsorption forcebetween the polishing workpiece and the sheet, thereby improving thepolishing effect of the polishing workpiece. Additionally, since no holestructure exists in the interior of both the surface layer and theslightly rough layer, the slurry will not be inhaled during thepolishing, thus prolonging the lifetime of the sheet.

Another objective of the present invention is to provide a method formaking the sheet for mounting a polishing workpiece, which comprises thefollowing steps:

(a) forming a surface layer on a release paper, the surface layer havingno hole structure in the interior thereof;

(b) forming a substrate on the surface layer;

(c) drying the surface layer and the substrate;

(d) removing the release paper; and

(e) printing a slightly rough layer on the surface layer, the slightlyrough layer having no hole structure in the interior thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of the polishing device with aconventional sheet disclosed in U.S. Patent No. U.S. Pat. No. 5,781,393;

FIG. 2 shows a local schematic view of the sheet of FIG. 1;

FIG. 3 shows a local schematic view of the sheet for mounting thepolishing workpiece according to the present invention; and

FIGS. 4 to 6 show schematic views of each process step of the method formaking the sheet for mounting the polishing workpiece according to thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 3, a local schematic view of the sheet for mountingthe polishing workpiece according to the present invention is shown. Thesheet 2 of the present invention is of a three-layered structure, whichcomprises a substrate 21, a surface layer 22 and a slightly rough layer23. The substrate 21 has a first surface 211 and a second surface 212,wherein the second surface 212 is used for being adhered on the lowerbase plate (not shown) of a polishing device. In this embodiment, thematerial of the substrate 21 is high solid PU, with a plurality ofcontinuous or discontinuous type holes 213 existing in the interior ofthe substrate 21, and the thickness of the substrate 21 can be largerthan 0.5 mm. However, it is to be understood that the material of thesubstrate 21 may also be acrylic resin or another kind of resin.

The surface layer 22 is located on the first surface 211 of thesubstrate 21, and has a surface 221. The surface layer has no holestructure in the interior thereof. The material of the surface layer 22is a polymeric elastomer without foam (for example PU, acrylic resin oranother kind of resin). The surface layer 22 has a uniform thicknesswhich is less than that of the substrate 21. The materials of thesurface layer 22 and substrate 21 may be the same or different.

The slightly rough layer 23 is located on the surface 221 of the surfacelayer 22, and is used for carrying and mounting a polishing workpiece(not shown). No hole structure exists in the interior of the slightlyrough layer 23, and the material of the slightly rough layer 23 is apolymeric elastomer without foam (for example PU, acrylic resin oranother kind of resin). The materials of the slightly rough layer 23 andsurface layer 22 may be the same or different. A vent space 232 isformed between any two protrusions 231 of the slightly rough layer 23,and when the polishing workpiece contacts the slightly rough layer 23,the air therebetween may be easily vented out via the vent space 232,without the phenomenon of air wrapping, which increases the adsorptionforce between the polishing workpiece and the sheet 2, thereby improvingthe polishing effect of the polishing workpiece. Additionally, since nohole structure exists in the interior of both the surface layer 22 andthe slightly rough layer 23, the slurry will not be inhaled during thepolishing, thus prolonging the lifetime of the sheet 2.

The present invention further relates to a method for making the sheetfor mounting a polishing workpiece, which comprises the following steps.

At first, referring to FIG. 4, a surface layer 22 is formed on a releasepaper 30. The surface layer 22 has no hole structure existing in theinterior thereof. The surface layer 22 has a surface 221. The materialof the surface layer 22 is a polymeric elastomer without foam (forexample PU, acrylic resin or another kind of resin), and the surfacelayer 22 has a uniform thickness. Preferably, the surface layer 22 isformed on the release paper 30 in a manner of coating.

Then, referring to FIG. 5, a substrate 21 is formed on the surface layer22, the substrate 21 has a first surface 211 and a second surface 212.In this embodiment, the material of the substrate 21 is high solid PU,with a plurality of continuous or discontinuous type holes 213 existingin the interior of the substrate 21, and the thickness of the substrate21 is larger than 0.5 mm. However, it is to be understood that thematerial of the substrate 21 may also be acrylic resin or another kindof resin. The materials of the surface layer 22 and the substrate 21 maybe the same or different. Preferably, the substrate 21 is formed on thesurface layer 22 in a manner of coating. Therefore, compared with theconventional wet process, the substrate 21 of the invention can remain auniform thickness when the thickness thereof is larger than 0.5 mm.

Then, the substrate 21 and surface layer 22 are dried for one day. Afterthat, the release paper 30 is removed.

At last, referring to FIG. 6, after turning the substrate 21 and thesurface layer 22 upside-down for 180 degrees, a slightly rough layer 23is printed on the surface 221 of the surface layer 22 to form the sheet2 (the same as FIG. 3). No hole structure exists in the interior of theslightly rough layer 23, and the material of the slightly rough layer 23is a polymeric elastomer without foam (for example PU, acrylic resin oranother kind of resin). The materials of the slightly rough layer 23 andsurface layer 22 may be the same or different. In this embodiment, theprinting step is screen printing.

Preferably, a water repellent treatment may also be performed for theslightly rough layer 23 to prolong the lifetime of the sheet 2.

While several embodiments of the present invention have been illustratedand described, various modifications and improvements can be made bythose skilled in the art. The embodiments of the present invention aretherefore described in an illustrative but not restrictive sense. It isintended that the present invention may not be limited to the particularforms as illustrated, and that all modifications which maintain thespirit and scope of the present invention are within the scope asdefined in the appended claims.

1. A method for making a sheet for mounting a polishing workpiece,comprising the following steps of: (a) forming a surface layer on arelease paper, the surface layer having no hole structure in theinterior thereof; (b) forming a substrate on the surface layer; (c)drying the surface layer and the substrate; (d) removing the releasepaper; and (e) printing a slightly rough layer on the surface layer, theslightly rough layer having no hole structure in the interior thereof.2. The method as claimed in claim 1, wherein the substrate has aplurality of holes in the interior thereof.
 3. The method as claimed inclaim 2, wherein the holes of the substrate are of a continuous type. 4.The method as claimed in claim 2, wherein the holes of the substrate areof a discontinuous type.
 5. The method as claimed in claim 1, whereinthe surface layer is formed on the release paper in a manner of coatingin the step (a).
 6. The method as claimed in claim 1, wherein thesubstrate is formed on the surface layer in a manner of coating in thestep (b).
 7. The method as claimed in claim 1, wherein the slightlyrough layer is printed on the surface layer in a manner of screenprinting in the step (e).
 8. The method as claimed in claim 1, furthercomprising a step of performing a water repellent treatment for theslightly rough layer.